1. Field of the Invention
The field of art to which the invention pertains is water containing solvent systems of nitrogen containing carbon compounds, compositions and methods of making the same.
2. Description of the Prior Art
With increased awareness of environmental pollution and energy resource depletion, attempts have been made to eliminate the need for organic solvent systems for polymer solutions. One approach to this problem has been the use of polymer systems which can be used in the hot melt state. Note, for example, U.S. Pat. No. 4,075,179. Another approach to this problem has been a replacement of organic solvents with water solutions. However, one problem which has been encountered in attempting to work up aqueous solutions of useful industrial polymers is the limited solubility of such polymers in water. Accordingly, it has been necessary to either start with low molecular weight polymers; mix water with organic solvent systems; build high acid numbers into the polymers; use strong bases in conjunction with the water to dissolve such polymers; and/or use dilute solutions of low solubility polymers.
For example, U.S. Pat. No. 3,737,478 which teaches polymer systems using water as a solvent, specifically requires large amounts of organic solvent and requires large amounts of strong bases to obtain useful degrees of water solubility. Furthermore, such polymer compositions are used in relatively low solids concentration. The starting polymers of this system also require relatively high acid values. In these typical prior art systems, to attain useful degrees of solubility, materials of relatively low molecular weights and high acid values are used as starting materials. Since these materials are of low molecular weight, it is necessary to include various additives, both reactants and catalysts, to these water systems to attain polymer molecular weights high enough to impart useful properties in use, for example, after application to a wire. In addition to complicating the chemistry involved in utilizing such polymers, these additives lend a certain degree of unpredictability and difficulty of standardization to the final products.
Accordingly, what is needed in the art is a method of making aqueous solutions of polymers which can be solubilized at high molecular weights without the addition of large amounts of organic solvents, and with high polymer solids content without regard for possible low acid numbers of the polymeric starting material.